Wounds in general, as used in this context, are breaks in the integrity of the skin of a patient. Wounds may occur by several different mechanisms. One such mechanism is through mechanical traumatic means such as cuts, tears, and abrasions. There are many instruments of causality for mechanical wounds, including a kitchen bread knife, broken glass, gravel on the street, or a surgeon's scalpel. A different mechanism cause for mechanical wounds is the variable combination of heat and pressure, when the heat alone is insufficient to cause an outright burn. Such wounds that result are collectively referred to as pressure sores, decubitus ulcers, or bed sores, and reflect a mechanical injury that is more chronic in nature.
Another type of mechanism causing a wound is vascular in origin, either arterial or venous. The blood flow through the affected region is altered sufficiently to cause secondary weakening of the tissues which eventually disrupt, forming a wound. In the case of arterial causes, the primary difficulty is getting oxygenated blood to the affected area. For venous causes, the primary difficulty is fluid congestion to the affected area which backs up, decreasing the flow of oxygenated blood. Because these wounds represent the skin manifestation of other underlying chronic disease processes, for example, atherosclerotic vascular disease, congestive heart failure, and diabetes, the vascular injuries also are chronic in nature, forming wounds with ulcerated bases.
Traditional wound coverings, such as bandages, are used to mechanically cover and assist in closing wounds. Such bandages typically cover the wound in direct contact with the wound. This may be acceptable for acute, non-infected traumatic wounds, but it must be kept in mind that direct bandage contact with a wound can interfere with the healing process. This interference is particularly prevalent for chronic ulcerated wounds because of the repeated mechanical impact and interaction of the bandage with the fragile, pressure sensitive tissues within the wound.
The benefits of application of heat to a wound are known, and documented benefits include: increased cutaneous and subcutaneous blood flow; increased oxygen partial pressure at the wound site; and increased immune system functions, both humoral and cell mediated, including increased migration of white blood cells and fibroblasts to the site.
However, heat therapy for the treatment of wounds, either infected or clean, has been difficult to achieve in practice. For instance, heating lamps have been used, but these resulted in drying of wounds, and in some cases, even burning tissue from the high heat. Due to these and other difficulties, and since most acute wounds usually heal over time, physicians no longer consider the application of heat to the wound as part of the treatment process. The thinking among medical personnel is that any interference in a natural process should be minimized until it is probable that the natural process is going to fail. Additionally, the availability of antibiotics for use in association with infected wounds has taken precedence over other therapies for the treatment of chronic wounds and topical infections.
In French patent number 1,527,887 issued Apr. 29, 1968 to Veilhan there is disclosed a covering with rigid oval dome, its edge resting directly on the patient's skin. One aspect of the Veilhan wound protector is a single oval heating element resting on the outer surface of the rigid dome, positioned at the periphery of the rigid dome. Veilhan does not discuss the heating aspect other than to state that it is a component.
The benefits of controlling other environmental parameters around the wound site are not as well known. Controlling the humidity at the wound site and the benefits of isolating the wound have not been extensively studies and documented.
While the benefit of applying heat to wounds is generally known, the manner of how that heat should be used or applied is not known. Historically, heat was applied at higher temperatures with the goal of making the wound hyperthermic. These higher temperatures often resulted in increasing tissue damage rather than their intended purpose of wound therapy and healing. There is a need for appropriate wound care management incorporating a heating regimen that is conductive to wound healing, yet safe and cost effective.